Carex cephaloidea (Thin-leaf Sedge)

Plant Info
Also known as: Cluster-bracted Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:sun; moist to dry; rich woods, forest edges, thickets, stream banks
Fruiting season:June - July
Plant height:1 to 4 feet
Wetland Indicator Status:GP: none MW: FACU NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Spikes: Flower shape: indistinct Cluster type: spike

[photo of flowering spikes] A cluster ½ to 1½ inches long at the top of the stem, made up of 5 to 10 round to oval spikes, the uppermost spikes tightly crowded, the lower spikes more separated but by less than twice the length of the lowest spike. The terminal spike has staminate (male) flowers at the tip and pistillate (female) flowers at the base (androgynous), with the lateral spikes usually androgynous though some may be all pistillate. At the base of the lowest spike may be a slender bract up to about ¾ inch long that does not overtop the terminal spike, but bracts are often absent altogether.

Leaves and stems: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of sheath and ligule] Leaves are basal and alternate, mostly near the base, thin, mostly floppy, the largest 4 to 8 mm wide, shorter than to a little longer than the flowering stems, though vegetative shoots may be longer. Stem leaf sheaths loosely wrap the stem and are translucent whitish, cross-wrinkled (rugose), fragile and easily torn. The ligule (membrane where the leaf joins the sheath) is about as long as or slightly longer than wide. Leaves are hairless and V-shaped in cross-section when young.

[photo of base] The back of the sheath is longitudinally green and white striped or mottled, with green cross-veins. Bases are wrapped in a brown sheath that may become fibrous with age. Stems are erect to ascending, up to 4 mm wide at the base and much more slender above, 3-sided, very rough textured on the upper stem, elongating up to 4 feet at maturity. Plants are clump-forming and not colony-forming.

Fruit: Fruit type: seed without plume

[close-up of maturing spikes] Fruit develops in late spring through early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Pistillate spikes each contain 6 to 20 fruits that are spreading to ascending and crowded on the stalk.

[photo of perigynia, scale and achene] Pistillate scales are egg-shaped to nearly round, translucent white or tinged brown, with a green midrib, blunt or pointed at the tip, sometimes the midrib extending to a very short awn, and are about half as long as the perigynia. Perigynia are 3 to 4.5 mm long, 1.5 to 2.5 mm wide, green at maturity except yellowish at the base, obscurely 4 to 7-veined, narrowly winged, hairless but with minute teeth along the wing edge on the upper half, not much inflated but spongy at the base, flattened on the back side, generally lance-shaped in outline, widest near the middle tapering to a toothed beak up to 1.3 mm long. Achenes are 1.6 to 2 mm long, up to 1.7 mm wide, flattened lens-shaped, nearly round in outline, and mature to brown.

Notes:

Carex cephaloidea is found primarily in deciduous woods and reaches the northwest tip of its range in Minnesota.

Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex cephaloidea is in the Phaestoglochin section; some of its common traits are: clump forming, basal sheaths usually fibrous, sheath fronts cross-wrinkled (rugose), leaves hairless and V-shaped in cross-section when young, 3 to 15 stalkless spikes (rarely the lower are branched), terminal spike with staminate flowers at the tip (androgynous), lateral spikes androgynous or all pistillate, perigynia ascending to spreading and flattened on the back side, rounded and spongy at the base, beaked, the beak usually toothed, flattened lens-shaped achenes.

Carex cephaloidea is distinguished by its woodland habitat, loose sheaths cross-wrinkled on the front and green and white striped or mottled on the back, 5 to 10 round to oval spikes, often lacking bracts, all near the tip and overlapping but distinctly separated, the lowest by less than twice the length of the spike, spikes with 20 or fewer perigynia that are spreading to ascending, perigynia narrowly winged, flattened on the back side, 3 to 4.5mm long, green at maturity, and pistillate scales about half as long as the perigynia. Most similar are Carex cephalophora and Carex sparganioides, both of which may be found in a similar habitat, and Carex gravida, which is found in more open spaces. C. cephalophora has more tightly crowded spikes without any visible separation and sheaths that are tight, thickened at the tip and not cross-wrinkled. C. gravida has pistillate scales nearly as long as the perigynia and its sheaths are not cross-wrinkled or only weakly so. C. sparganioides has spikes not all crowded at the tip, the lowest 2 to 4 separated by twice or more the length of the spike, and has 15 to 50 (average 20 or so) perigynia per spike.

Please visit our sponsors

  • Minnesota Native Plant Society

Where to buy native seed and plants ↓

Map of native plant purveyors in the upper midwest

  • Shop for native seeds and plants at PrairieMoon.com!
  • Shooting Star Native Seeds - Native Prairie Grass and Wildflower Seeds
  • Morning Sky Greenery - Native Prairie Plants
  • Minnesota Native Landscapes - Your Ecological Problem Solvers
  • Natural Shore Technologies - Using science to improve land and water

More photos

Photos by K. Chayka taken in Winona County. Photos courtesy Peter M. Dziuk taken in Fillmore and Winona counties.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Post a comment

Note: All comments are moderated before posting to keep the riff-raff out. An email address is required, but will not be posted—it will only be used for information exchange between the 2 of us (if needed) and will never be given to a 3rd party without your express permission.

For info on subjects other than plant identification (gardening, invasive species control, edible plants, etc.), please check the links and invasive species pages for additional resources.



(required)




Note: Comments or information about plants outside of Minnesota and neighboring states may not be posted because Id like to keep the focus of this web site centered on Minnesota. Thanks for your understanding.